* {
    margin: 0;
    padding: 0;
}

.top {
    height: 50px;
    background-color: gray;
    display: flex;
    justify-content: space-around;
    align-items: center;
}

.top > div {
    display: flex;
}

.top + div {
    display: flex;
}

.top > div:nth-child(2) > div {
    margin: 0 20px;
}

.left {
    height: calc(100vh - 50px);
    width: 200px;
    background-color: lightpink;
}

.right {
    height: calc(100vh - 50px);
    width: calc(100vw - 200px);
    background-color: lightyellow;
}

/*用户中心*/
.userCenter > div:nth-child(2) {
    display: none;
    position: absolute;
    border: 1px solid red;
    background-color: lightpink;

}

.userCenter > div:nth-child(2) > div {
    line-height: 30px;
    padding: 0 10px;
}

.userCenter:hover .aa {
    display: block;
}

/*左边导航管理*/
.left {
    text-align: center;
}

.left > div {
    cursor: pointer;
    margin: 10px 0;
}

.left > div > div:nth-child(2) > div:hover {
    background-color: lightblue;

}

.left > div > div:nth-child(2) {
    text-indent: 2em;
    display: none;
    color: gray;
}

.left > div:nth-child(1) > div:nth-child(2) {
    display: block;
}

/*.left > div:hover .bb {*/
/*    display: block;*/
/*}*/